In order to optimize the nominal diameter, pressure, torque, life, and other technical parameters of the ball valve, in recent years, there are a wide variety of valve complex opening and closing mechanisms.
Chinese patent No. 200720082066 has disclosed a low-torque ball valve, which provides a low torque valve comprising a valve body, a valve ball, a valve seat, a bearing seat, a valve rod, a driving device, and a valve ball bearing connection. The patent has several disadvantages. The structure of the driving device is complex, and extremely occupies the external space of the valve body. The driving device involves many parts, resulting in the complexity of the assembling process. The rotation angle for opening or closing the valve is 180 degrees. The working space formed by the valve rod and the driving device requires a very high quality of sealing process, thus the traditional sealing methods and processes are likely to cause leakage. In addition, since the cost of manufacturing the driving device is very high, it does not conform to the purpose for economy and environment friendly.
There has recently developed a guide slot lifting rod ball valve at domestic and abroad. There provided on the valve rod a S-shaped guide slot, which engages with the guide pin, so that when the valve rod rises, it causes the ball to disengage from the valve seat. Then, the valve rod further rotates 90° counterclockwise and fully open the valve. When the valve rod is moving down, the ball rotates 90° clockwise, then being pressed towards the valve seat to close the valve. The shortcomings of the technology is that a long S-shaped guide slot being provided on the valve rod, thus, when the valve rotates for opening or closing, the valve rod needs to move up and down spirally along the guide slot, resulting in a huge space for the guide slot and a large rotation angle and other shortcomings.
Chinese Patent Application No. 99124192.4 has disclosed a structure for opening and closing a valve, which is a disk-shaped two-track rotary with deploy-close structure. The structure comprises a fixed disk, a rotating disk and a stop pin. When the external force drives the valve rod together with the rotating disk to move the stop pin, the stop pin rotates clockwise along the “arc” track of the fixed disk. When rotated to the “straight” track connected to the “arc” rail track, the rotating disk rotates clockwise further, and the stop pin deploys the surrounding of the fixed disk along the “straight” track of the fixed disk under the forced action by the “deploy-close” track of the rotating disk. At this time, the stop pin structure together with the valve sealing structure close to the valve seat, thus close the valve. When the valve rotates counter-clockwise together with the rotating disk, the stop pin together with the sealing structure move towards the centre of the fixed disk along the “straight” track of the fixed disk under the forced action by the “deploy-close” track of the rotating disk, and then rotate counter-clockwise along the “arc” track of the fixed disk to open the valve. The technical shortcoming of the patent is to use the “arc connected with straight line” track, which requires high precision and complex processing. Further, since the valve cartridge is a combined sphere, it is difficult to get a balanced preload force, resulting in damage to the valve cartridge and shortening the life of the valve.
Chinese Patent No. 200620105067 has disclosed an orbit plug valve, comprising a valve body, a valve cover, an operating member, a valve rod, a valve seat, a valve plug which together with the valve seat forming a conical surface sealing, and an orbital mechanism. The orbital mechanism comprises a track with two guide slots mounting on the neck portion of the valve plug and a plate with two guide pins inserting into said guide slots, as well as a lock nut and an adjusting ring for adjusting the mounting position of the track. The shortcomings of the present patent are that the transmission device structure is complex, and extremely occupy the external space of the valve body. Further the transmission device involves more parts, resulting in complicated assembly process. In addition, since the valve has a plug forming a cone surface sealing as well as a lock nut and an adjusting ring for adjusting the mounting position of the track, it must be adjusted several times, resulting in complex operation.